Carbon nanotubes (CNTs) and CNTs-supported rhodium were tested as catalysts for NO decomposition. For the fresh catalysts, 100% NO conversion was achieved at 600 degrees C over CNTs; when 1 wt% Rh was loaded on CNTs, 100% NO conversion was achieved at 450 degrees C. If the catalysts were pre-reduced in H-2 at or above 300 degrees C, 100% NO conversions were observed at 300 degrees C. XPS investigation indicated that there was still metallic rhodium (BE = 307.2 eV) on Rh/CNTs after heating in air at 500 degrees C for 2 h and after the NO decomposition reaction. As for a 1 wt% Rh/Al2O3 sample, the rhodium (BE = 308.2 eV) was completely in the form of Rh2O3 after similar treatments. These results suggest that compared to gamma-Al2O3, the CNTs material is more capable of keeping the rhodium in its metallic state. The results obtained in H-2-TPR studies support this conclusion. In addition, TEM investigation revealed that the rhodium particles distributed rather evenly over CNTs with a particle diameter of around 8 nm. We propose that CNTs can be used as a material for the facilitation of NO decomposition.